PRINCIPLES OF TOXICOLOGY

16.13 TOXIC PROPERTIES OF REPRESENTATIVE HALOGENATED SOLVENTS 397
Local application of carbon tetrachloride to human skin produces distinct pain with erythema,
hyperemia, and wheal formation followed by vesiculation, which may facilitate secondary
infection. Studies have indicated that absorption of carbon tetrachloride through the skin may
present a potential problem based on a limited study on human subjects. In view of the potential
hepatotoxicity of carbon tetrachloride, repetitive contact of the skin with liquid carbon tetrachloride
should be prevented.
Vinyl chloride (see Figure 16.24) is a gas under ambient conditions, and is a potent skin irritant.
Contact with the liquid form may cause frostbite. The eyes may be immediately and severely irritated.
Vinyl chloride depresses the central nervous system, causing symptoms that resemble mild alcohol
intoxication. Lightheadedness, nausea, and dulling of visual and auditory responses may develop in
acute exposures. Severe vinyl chloride exposure has been reported to result in death. Workers entering
polyvinyl chloride reactor vessels for cleaning have exhibited a triad combining arthro-osteolysis,
Raynaud’s phenomenon, and scleroderma. Chronic exposure may damage the liver and induce a highly
specific liver cancer (angiosarcoma), which is an established risk for chronic exposures to vinyl
chloride at the old TLV ® of several hundred ppm. Increased rates of cancer of the lung, lymphatic, and
nervous systems have been reported. Experimental evidence links vinyl chloride to tumor induction
in a variety of organs, including liver, lung, brain, and kidney, and to nonmalignant alterations (fibrosis,
connective tissue deterioration).
Figure 16.24 Vinyl chloride.
The mutagenic, carcinogenic, and reproductive hazard of vinyl chloride is further discussed in
Chapters 11, 12, and 13, respectively.
Trichloroethene (TCE) and perchloroethene (PERC) (see structures in Figure 16.25) are among the
most widely used chlorinated solvents, on an historical basis. The toxicological literature is extremely
large for these substances, and the reader is referred to the ATSDR Toxicological Profiles for a more
detailed treatment of available information. These substances exhibit a generally low degree of acute
toxic potential, and industrial use experience has been relatively good in cases where appropriate
exposure controls were in place. Although historically both have been regulated as potential
carcinogens by some occupational and environmental regulatory agencies, recently the ACGIH
reclassified TCE in Group A5 (Not Suspected as a Human Carcinogen, and placed PERC in Class
A3 (Animal Carcinogen). The classification for both of these agents by U.S. EPA is under review
at this time. It is of interest to note that in some environmental conditions both TCE and PERC
may be degraded by sequential dechlorination to vinyl chloride, which was described previously
in this section.
Figure 16.25 TCE and PERC.